Underreamer



Oct. 17, 1961 M. H. SCHUTTE UNDERREAMER 2 Sheets-Sheet 1 Filed Feb. 21,1958 My/e: H \Scbu fze INVENTOR 7 ATTORNEYS Oct. 17, 1961 3,004,615

M. H. SCHUTTE UNDERREAMER Filed Feb. 21, 1958 2 Sheets-Sheet 2 My e:Jc/luffe INVENTOR.

BY 2 W514i,

3,9Mfil Patented Get. 17, 1961 3,064,615 UNDERREAMER Myles H. Schutte,4655 Telephone Road,

Houston 17, Tex. Filed Feb. 21, N58, Ser. No. 716,7t39 6 Claims. (Cl.175-486) This invention relates to new and useful improvements inunderreamers. y

In United States Letters Patent No. 2,401,515, granted June 4, 1946, toMyles G. Schutte and Normal L. Schutte, an underreamer is disclosed forforming an enlarged or underreamcd section in a previously formed holein the ground.

It is an object of this invention to provide an underreamer having allof the advantages of the underrearner disclosed in said Patent No.2,401,515, and in addition thereto, to provide certain new and usefulimprovements in such underreamer.

An important object of this invention is to provide a new and improvedunderreamer for reaming or cutting an enlarged or 'underreamed sectionin a previously formed hole in the ground wherein all of the weightwhich is applied to the underreamers acts in a direction to move theunderreamer blades outwardly during the cutting or underrearningtherewith, whereby an increased etficrency is obtained with theunderreamer of this invention.

Another object of this invention is to provide a new and improvedunderreamer having underrearner blades which are adapted to be movedoutwardly at their lower ends as they are rotated to thereby graduallyenlarge a section of a hole in which the underrearner is used, whereineach of said blades is mounted on a pivot pin near its upper end and aguide pin near its lower end, and wherein such pins for each blade arein substantially vertical alignment when each blade is in the retractedposition so that upon a downward force being applied to each blade, thefull amount of such force is exerted in the direction of movement of theblade as it moves outwardly from its retracted position to its fullyextended position.

A further object of this invention is to provide a new and. improvedunderrearner having underrearner blades which are adapted to be movedoutwardly at their lower ends as they are rotated to thereby graduallyenlarge a section of a hole in which the underreamer is used,whereineach of said blades is mounted on a separate pivot pin near itsupper end so that only the blade mounted on each pivot pin is exerting arotational force thereon during the pivotal movement of such blade,whereby the wear on each pin and each blade is minimized.

The preferred embodiment of this invention will be describedhereinafter, together with other features thereof, and additionalobjects will become evident from such description.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawingsforming a part thereof, wherein an example of the invention is shown,and wherein:

FIG. 1 is a vertical view, partly in section and partly in elevation,illustrating the apparatus of this invention;

FIG. 2 is a side view of the device of this invention taken on line 2 2of FIG. 1, and it is shown partly in elevation and. partly in section;

7 FIG. 3 is a horizontal sectional view taken on line 3-3 of FIG. 1;

FIG. 4 is a view similar to FIG. 2, but illustrating the apparatus ofthis invention in an extended position for reaming a hole in the ground;

FIG. 5 is an isometric view of the cross-head construc- 2 7 tion whichis preferably utilized in connection with the apparatus shown in FIGS.1, 2 and 4; and

FIG. 6 is a horizontal sectional view similar to FIG. 3,

but illustrating a modified construction wherein a single upper pivotpin or rod is utilized instead of the two separate rods which areutilized in the form shown in FIG. 3 of the drawings.

in the drawings, the letter A designates generally the underreamer bodyof the underreamer of this invention. The underreamer body A has mountedtherewith one or more underrearner or reamer blades R and R. Such reamerblades R and R are mounted on the body A in a particular manner formoving such blades R and R from a retracted position (FIGS. 1 and 2) toan extended reaming position (FIG. 4). As will be explained in detailhereinafter, the rearner blades R and R are moved outwardly by theapplication of a downward force thereon, and during such outwardmovement of the blades R and R, the entire apparatus is rotated .toeffect the reaming or cutting of an enlarged section in a previouslydrilled or formed hole in the ground. Normally, such enlarged section ofthe hole is formed at the lower end thereof and therefore the apparatusrests upon the lower surface of the hole in the ground as it is rotatedand the blades R and R are forced outwardly during the reamingoperation.

In the preferred embodiment of this invention as illustrated in thedrawings, the underreamer body A includes laterally spacedlongitudinally extending vertical side plates It) and to, each of whichis substantially rectangular in shape and is preferably identical withthe other side plate. The lower ends of the side plates 10 and iii arewelded or otherwise connected to a lower plate 11 which would normallybe circular in shape. The lower ends of the side plates 10 and 10 arethus maintained in a particular selected laterally spaced relationship.Also, the lower plate ll of the body A is adapted to rest upon the lowersurface or bottom of a previously formed hole in the ground during thereaming operation with the apparatus of this invention. In such manner,when a downward force is applied to the plates R and R, as will beexplained hereinafter, the body A is prevented from moving downwardlybecause of the contact of-the lower plate 11 with the bottom surface orlower wall of the hole in the ground. The upper ends of the plates 10and 10 are welded or are otherwise connected to laterally extendingconnector plates 214 and 15. The upper ends of the side plates 10 and 10are also welded or otherwise connected to an upper disk or plate 16which is preferably circular in construction and is formed with acentral hole 16a which is square in shape in the usual case. However,such opening 16a may have a lesser or a greater number of side surfacesso long as it is polygonal for a purpose to be hereinafter described. Anannular skirt or shield 18 which is in the form of a cylinder in theusual case is welded or otherwise connected to the periphery of theupper disk 16.

The plate 10 has an inclined or diagonal slot 19* formed therethroughfor receiving a rod or bolt 20. As illustrated in the drawings, theplate 10 may have an additional reinforcing plate section 21 welded orotherwise secured thereto which is provided with an inclined slot 22.The slot 22 is coextensive and is aligned with the slot 19 so as to forma continuation thereof through which the rod or bolt 20 also extends.The rod or bolt 20 is connected or attached to the reamer blade R by anysuitable means, but ,as illustrated in the drawings, such rod or pin 20is in the form of a bolt and its head 23 is positioned to the outside ofthe'reinforcing plate section 21 so as to be on the opposite side of theside plate 10 from the reamer blade R. The bolt 20 is will be moreevident hereinafter.

threaded in the usual manner and has a nut 24 threaded thereon for'engagement with the reamer blade R to hold same substantially paralleland adjacent to the side plate as shown in FIG. 1. It will be recognizedthat other suitable means can be utilized for connecting the reamerblade R to the rod, pin or bolt 20, but the bolt as illustrated in thedrawings is preferred because it is removable for replacing the blade Rwhen it becomes worn or damaged. Also, the bolt 21), by reason of itshead 23, prevents lateral shifting of the reamer blade R away from theside plate 10 as the pin or rod 20 moves within the slots 19 and 22.Preferably, a bushing or wear sleeve formed of metal or other hardwearing material is positioned around the portion of the rod, pin orbolt 20 which is in contact with the walls of the slots 19 and 22 sothat such bearing sleeve 25 may be replaced when it becomes worn duringuse.

The side plate 10 also is provided with a vertical opening 26 which ispositioned substantially vertically above the upper end of the slots 19and 22. A reinforcing plate section 27 is welded or is otherwise securedto the exterior of the side plate 10 and it is formed with an opening 28which is also substantially vertical and is coexten:

sive and in alignment with the opening 26 so as to form a continuationthereof located substantially directly above the upper end of theinclined or diagonal slots 19 and 22.

In the preferred form of the invention, the side plate 10 also has asecond substantially vertical opening 29 (FIG. 3) which is parallel withthe opening 26 in the side plate 10 and which is positioned so as to besub stantially vertically above the lower end of the slots 19 and 22. Areinforcing plate section 30 is welded or is otherwise secured to theoutside of the side plate 10 and such reinforcing section 30 has asubstantially vertical opening 31 formed therethrough which iscoextensive with and is in alignment with the opening 29 so as to form acontinuation thereof. A pivot pin or rod 35 which is provided with ahead 35a at one end thereof and another head 35b at the other endthereof, extends through the slots 26 and Z8 and also is connected withthe upper end of the reamer blade R. A wear ring or sleeve 36 surroundsthe rod or pin 35 at the portion thereof which is confined within thewalls of the slots 26 and 28 so that when such sleeve 36 becomes worn ordamaged during use, it may be replaced without replacing the entire r-odor pin 35. The heads 35a and 35b on the rod or pin 35 may be welded orotherwise afiixed to the rod 35 and they prevent lateral shifting of therod 35 with respect to the side plates 10 and 10, as The reamer blade Ris formed with an opening 37 near its upper end through which the rod orpin 35 extends. Preferably, a wear tube or pipe 38 surrounds the pin 35and also extends into the bore or opening 37 of the reamer blade R. Aswill be explained hereinafter, downward movement of the pin 35 isimparted to the upper end of the reamer blade R to move same downwardlywhile permitting a pivotal movement of the upper end of the reamer bladeR about the pin or rod 35. Likewise, upon an upward movement of the rodor pin 35, the reamer blade R is permitted to pivot relative to thepivot pin or rod 35.

A second pivot pin or rod 40 having heads 40a and 40b at each endthereof extends through the slots 29 and 31 (FIG. 3). A wear ring orsleeve 41 is provided at the end of such rod 40 which is disposedbetween the walls of the slots 29 and 31 for replacement and repairpurposes. The rod 40 also extends through a substantially square shapedspacer 42 which is of substantially the same thickness as the upper endof the reamer blade R.

The pivot pins or rods 35 and 40 extend from the side plate 10 to theside plate 10 and the rod 40 is connected to the reamer blade R (FIG.3). The parts of the apparatus connected to the side plate 10" whichcorrespond with the parts mounted on the side plate 10 have the samenumerals as such parts on the side plate '10 except that a prime markhas been added after the numerals for the parts positioned with the sideplate 10. Thus, the side plate 10 has inclined or" diagonal slots 19'and 22' corresponding with the diagonal or inclined slots 19 and 22,except that the inclination of the slots 19' and 22 is at an equal andopposite angle to the slots 19 and 22 as seen by the dotted linesidentified with the numeral 19 in FIG. 4 of the drawings. The opening 22is formed in a side reinforcing plate section 21 which corresponds withthe section 21 except that it is formed in an equal and oppositedirection of inclination as compared with the plate 21. The plate 10also has substantially vertical slots or openings 2'6 and 23 which formone slot at the upper end of the body 10 and also slots 29 and 3 1'which form another vertical slot at the upper end of the body 10. Therod or pin 35 extends through the slot formed by the vertical openings29 and 31 so that the end of such rod or pin 35 on the right (as viewedin FIG. 1) is guided in the same direction and path as the end at theleft (as viewed in FIG. 1) adjacent to the reamer blade R. In otherwords, as best seen in FIG. 3, the substantially vertical slot formed bythe slots or openings 26 and 28 are in lateral alignment with thesubstantially vertical opening formed by the slots or openings 29 and 31on the side plate 10; The pivot rod or pin 40 likewise extends throughthe reamer blade R and through the longitudinal or vertical slot formedby the openings or slots 26 and 28, and such slots 26 and 28' are insubstantially lateral alignment with the longitudinal or vertical slotformed by the openings 29 and 31. It should also be noted that thesubstantially vertical slot formed by the slots 26 and 28 is positionedsubstantially vertically above the upper end of the inclined or diagonalslot formed by the openings 19" and 22. Thus, the arrangement of the twosubstantially vertical slots and the inclined slot in the plate 10 is inreverse as compared to the arrangement of the two substantially verticalslots and the inclined slot in the side plate '10, so that for eachblade, its upper pivot pin is positioned substantially directly aboveits lower guide pin when each such blade is in the retracted position,while at the same time obtaining the opposite direction of movement ofthe blades outwardly during a reaming operation.

A spacer 42' which may be of any shape,-but preferably is square inshape as is the spacer 42, is mounted on the rod 35 and is ofsubstantially the same thickness as the thickness of the reamer blade R.Wear rings 36' and 41 are also preferably utilized in connection withthe pivot rods 41 and 35, respectively.

The lower guide rod, pin or bolt 20 corresponds with the rod, pin orbolt 20 and it has a head 23 therewith which is positioned outside ofthe reinforcing plate section 21. The bolt 20 is formed with the usualthreads and a nut 24 is connected thereto for attaching such bolt 20 tothe reamer blade R so that as the reamer blade R is moved downwardly atits upper end by the vertical guiding of the pin 40, the intermediate orlower portion of the plate R is guided in an outward direction by reasonof the bolt or pin 20 moving in its inclined or diagonal slot formed bythe openings 19 and 22'. Such movement is of course in an equal andopposite direction as compared with the direction of movement of thepin, bolt or rod 20.

For imparting the downward movement to the reamer blades R and R duringa reaming operation, the upper ends of the blades R and R are connectedwith a crosshead C (see FIG. 5 in particular). The cross-head C isformed with a substantially U-shaped block having sides 50 and 51 and anupper portion 52 which is formed integrally or is otherwise secured tothe sides 50 and 51. The side 50 of the cross-head C has openings 50aand 50b formed therethrough (FIG. 3). And similarly, the side 51 hasopenings 51a and 51b formed therethrough. The wear tube or pipe 38extends through the openings 50a and 51a and serve as wear surfaces andreinforcing for the pivot pin or rod 35. It will be noted that h Weartube or pipe 38 extends from the opening 51a therethrough and thenthrough the opening 50a and through the opening 37 in the rearner bladeR, but preferably such pipe 38 does not extend through the bracket orspacer 42', although such extension of the pipe or tube 38 through thecentral opening of the bracket 42' may be accomplished if so desired. Asimilar wear tube or pipe 55 extends from the opening 50b therethroughand then through the opening 51b, and preferably through the opening atthe upper end of the reamer blade R (FIG. 3). The pipe or tube 55 may ofcourse extend through the spacer or bracket 42 if so desired. It is tobe noted that the spacers 42 and 42 serve as contact surfaces for thesides 50 and 51 at the respective ends opposite from the reamer blades Rand R (FIG. 3).

The cross-head C has a square shank 56 welded or otherwise secured tothe upper end of the upper portion 52 of the cross-head C and suchsquare shank 56 extends through the square opening 16a in the disk orplate 16 so that rotational movement imparted to the shank 56 istransmitted directly to the disk 16 and thus to the body A which iswelded thereto. Of course, as pre 'viously pointed out the opening 16amay be polygonal and the shank '56 will have a corresponding number ofsides whether the number of such sides are four or some other lesser orgreater number. The important thing is that the shank 56 be verticallymovable relative to the disk 16 while being capable of transmittingrotational movement from the shank 56 to the disk 16.

It is also desirable to have a removable kelly-section 58 which servesas the driving shaft for the cross-head C and therefore for the entireunderreamer apparatus of this invention. The kelly 58 is likewisepolygonal and in the preferred form of the invention is square in shapeand it extends into a square opening 56a formed in the upper end of theshank 56. A retaining pin 59 extends from the shank 56 into the squarekelly 58 (FIGS. 1, 2, 4 and .5) to releasably retain such kelly 58within the shank 56 for imparting rotational movement from the kelly 58to the shank 56 in the known manner. A cot ter .key 60 or similarreleasable locking member is preferably employed with the connecting pin59 to hold same in position during use.

The construction of the reamer blades R and R may be varied within theskill of the art, but preferably each of such blades has an outwardlyflared or curved portion 61 with a cutting edge 62 formed thereon (-FIG.1).

In the use or operation of the device of this invention, the device orapparatus is lowered into a previously drilled or formed hole in theground. During such lowering operation, the blades R and R are retractedto the position shown in FIGS. 1 and 2 of the drawings wherein the outercutting edges of such blades R and R are within the confines of theshield or cover .18 and also the bottom plate 11 so that such blades Rand R do not interfere with the lowering of the apparatus to the lowerend or portion of the hole which is to be underreamed or enlarged. Whenthe plate 11 reaches the bottom or lower part of the hole which is to beenlarged, a downward force is applied to the blades R and R by imposingweight on the cross-head C through the drive shaft or kelly 58 and thedrive shank 56. The downward movement is imparted ;-to the blades R andR from the crosshead C by reason of the connection of such cross-head Cwith the pivot pins 35 and 46 which are pivotally connected to thereamer blades R and R. During the imposing of the weight or downwardforce upon the blades R and R, the driving shaft 58 is rotated with anyknown type of rotary table or other suitable means so as to rotate theentire apparatus illustrated in the drawings.

One of the important features of this invention resides in thetranslation or conversion of all of the downward force applied on theblades R and R to a force in the direction of movement of the blades Rand R in their respective inclined or diagonal slots. This isaccomplished because of the particular construction of this inventionwherein the .pivot pins or rods at the upper ends of the blades R and Rare in substantiatlly vertical alignment with the lower guide pins orrods on the blades R and R. Thus, the pin 35 which is connected to theupper end of the reamer blade R is substantially vertically above theguide rod or pin 23 which is positioned in the inclined slot formed bythe inclined openings or slots 19 and 22. All of the downward forceapplied to the blade R is thus translated or converted to a force in thedirection of the inclined slot formed by such inclined openings or slots19 and 22. Similarly, with respect to the reamer blade R, the downwardforce imparted to the cross-head C is transmitted from the pin or rod 40substantially vertically to the lower pin or rod 20' so that all of thedownward or substantially vertical force which is imparted to the bladeR is translated into movement in the direction of the diagonal orinclined slot formed by the openings 19 and 22'.

Thus, throughout the underreaming operation, as the apparatus of thisinvention is rotated and as the downward force is imparted to the bladesR and R to gradually move same outwardly to the fully extended reamingposition which has almost been reached in the illustration of FIG. 4 ofthe drawings, the downward force imparted from the cross-head C isalways acting in a direction to force such blades R and R outwardly inopposite directions with respect to each other and therefore theapparatus of this invention is greatly improved in efiiciency ascompared with prior known constructions.

Furthermore, since each blade is pivotally mounted at its upper end to aseparate rod, there is no resistance to the pivotal movement of eachblade about its upper pivot rod such as may occur when two blades havetheir upper ends mounted on the same pivot rod and are acting inopposite pivotal directions thereon during the outward swinging of theblades.

In FIG. 6 a sectional view of a modified form of the invention isillustrated, and such sectional View corresponds with the sectional viewillustrated in FIG. 3 for the first form of the invention. The onlychange of any consequence which is involved with respect to themodification of FIG. 6 resides in the use of a single pivot pin or rodin the modified construction of FIG. 6 rather than the two separate rods35 and '40. The modified pivot pin or rod of FIG. 6 is identified withthe numeral 75 and it takes the place of the two separate pivot rods 35and 40 of FIGS. l5. The end of the rod or pin 75 which extends throughthe upper end of the reamer blade R also extends through the opening 50aof the side 50 of the cross-head C and it further extends through theside plate 10 and the reinforcing plate 127 which in this form of theinvention extends for the full width of the side plate 10 since only oneopening formed by the vertical slots 12.8 and 126 is necessary with thesingle pin 75. On the portion of the rod 75 which extends through thereamer blade R at its upper end, the side 51 of the crosshead C isformed with the opening 5112 through which the substantially lateralportion of the rod 75 extends. The rod 75 also extends through theopenings 126 and 128' formed in the side plate 10 and the reinforcingplate section 1 27, respectively. The upper ends of the reamer blades Rand R serve as spacers in FIGURE 6 since the single pivot rod or pin 75is utilized in the form of the invention of FIG. 6. The remainder of theapparatus .in the form of the invention of FIG. 6 is identical with thatexplained and disclosed-in connection with FIGS. 1-5 of the invention.It will be evident that a downward force is imparted to both of' thereamer blades R upon the application of a'weight or downward force fromthe cross-head 'C through the pin 75 to the blades R and R. The sameoperation therefore results for effecting the reaming or enlarging of asection of a hole which has previously been formed in the ground withthe apparatus of this invention. It should also be noted that the formof the invention of FIG. 6 can be further modified if so desired byomitting the connecting central portion 750 of the, rod 75 so that twopartial rods would be formed by just the two lateral portions 75a and75b thereof, and the central section 750 would be omitted. Suitablemeans on the inner ends of the portions or sections 75a and 75b forpreventing lateral shifting thereof would of course be provided bywashers or similar means corresponding with the heads or washers 75d and75e on the outer ends of the sections 75a and 7512 (FIG. 6).

The foregoing disclosure and description of the invention isillustrative and explanatory thereof and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

l. An underreamer, comprising an underreamer body having two spacedvertical side 'plates, a bottom member secured to the lower ends of saidvertical side plates to space said plates and serve as a base, each ofsaid plates having two substantially vertical slots laterally spacedfrom each other and an inclined slot therebelow, the inclined slots insaid plates being at substantially equal and opposite angles ofinclination with respect to each other, one of said vertical slots ineach side plate being substantially vertically above the upper end ofthe inclined slot in such plate, the other of said vertical slots ineach plate being in lateral alignment with said one of said verticalslots in the other plate, a pair of reamer blades, said side platesextending below said reamer blades, a first upper rod connected to oneof said reamer blades and extending through two of the laterally alignedvertical slots, said first upper rod being at substantially the upperend of its travel in the slot through which it extends when said one ofsaid reamer blades is in a retracted position, a first lower rodconnected to said one of said reamer blades and extending through one ofsaid inclined slots and being positioned at the upper end of suchinclined slot substantially vertically below said first upper rod whensaid one of said blades is in said retracted position, a second upperrod connected to the other of said reamer blades and extending throughthe other two of the laterally aligned vertical slots, said second upperrod being at substantially the upper end of its travel in the slotthrough which it extends when said other of said reamer blades is in aretracted position, a second lower rod connected to the other reamerblade and extending through the other of said inclined slots and beingpositioned at the upper end of such inclined slot substantiallyvertically below said second upper rod when said other reamer blade isin the retracted position, and means for applying a downward force tosaid blades simultaneously to move same outwardly in opposite directionsaway from said body.

2. An underreamer, comprising an underreamer body having two spacedvertical side plates, a bottom member secured to the lower ends of saidvertical side plates to space said plates and serve as a base, each ofsaid plates having a substantially vertical slot and an inclined slotthere-below, the inclined slots in said plates being at substantiallyequal and opposite angles of inclination with respect to each other, thevertical slot in each plate being substantially vertically above theupper end of the inclined slot in such plate, said vertical slots beinglaterally displaced with respect to each other, a pair of reamer blades,said side plates extending below said reamer blades, an upper rodconnected to both of said blades and extending through the vertical slotin each side plate, the ends of said upper rod being laterally displacedwith respect to each other, said upper rod being at substantially theupper end of its travel in the slots through which it extends when saidblades are in a retracted position, a first lower rod connected to oneof said blades and extending through the inclined slot in one of saidplates and being positioned at the upper end of such inclined slotsubstantially vertically below the vertical slot in said one of saidplates when said one of said blades is in the retracted position, asecond lower rod connected to the other of said blades and extendingthrough the inclined slot in the other of said plates and beingpositioned at the upper end of such inclined slot substantiallyvertically below the vertical slot in said other of said plates whensaid other of said blades is in the retracted position, and means forapplying a downward force to said blades simultaneously to move sameoutwardly in opposite directions away from said body. Q

3. An underreamer, comprising an underreamer body having two spacedvertical side plates, a bottom member secured to the lower ends of saidvertical side plates to space said plates and serve as a base, each ofsaid plates having a substantially vertical slot and an inclined slottherebelow, the inclined slots in said plates being at substantiallyequal and opposite angles of inclination with respect to each other, thevertical slot in each plate being substantially vertically above theupper end of the inclined slot in such plate, a pair of reamer blades,said side plates extending below said reamer blades, a first upper rodconnected to one of said blades and extending through a vertical slot inone of said plates, a first lower rod connected to said one of saidblades and extending through the inclined slot in said one of saidplates, said first upper and lower rods being at substantially the upperends of their travel in the slots through which they extend when saidone of said blades is in a retracted position, a second upper rodconnected to the other of said blades and extending through the verticalslot in the other side plate, a second lower rod connected to the otherof said blades and extending through the inclined slot in the other sideplate, said first upper rod and said second upper rod being laterallyoffset with respect to each other, said second upper and lower rodsbeing at substantially the upper ends of their travel in the slotsthrough which they extend when said other of said blades is in aretracted position, and means connected to said first upper rod and saidsecond-upper rod for applying a downward force to said bladessimultaneously to move same outwardly in opposite directions away fromsaid body.

4. The structure set forth in claim 3, wherein said means for applying adownward force to said blades includes a cross-head connected to saidfirst upper rod and said second upper rod for moving same in unison toeifect the simultaneous movement of said blades outwardly.

5. The structure set forth in claim 3, wherein said first upper rod andsaid second upper rod are separate from each other and are positionedparallel to each other in the same horizontal plane.

6. The structure set forth in claim 3, wherein said first upper rod andsaid second upper rod are interconnected so as to form a single memberwith said first upper rod and said second upper rod as the ends thereof.

Grifiin a Mar. 16, 1915 Schutte et al. June 4, 1946

